Trunk circuits



Oct- 13 1925.'v

H.`D. cuRRlER ET AL l TRUNK CIRCUITS Filed Feb. 4, 1920 `3 Sheets-Sheet 2 Zin/@MP5, l fzfmf'urrz'er itx .gear E 57517 A .HUE/Pris oct. 13,1925.

H. D. CURRIER 1-:1' A1.

TRUNK CIRCUITS f Filed IFeb. 4, 1920 3 Shoes-Sheet 5 JEF/'En @7 5 fTaI/UZZIUrrzEr m M NLMDQ.

' matic apparatus,

Patented Oct'. 13, 1925.

UNITED STATES 1,556,761 PATENT OFFICE.

HIRAIM D. CURRIER, OF CHICAGO, .A ND GEORGE n.. EATON, OF Oax PARK, ILLINOIS,

ASSIGNORS TO KELLOGG SWITCHBOARD AND SUPPLY'COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS. I

TRUNK CIRCUITS.

Application mea rebr'uary 4, 1920. serial No. 356,262.

T 0 all zczO/nv it ymay con-cem.'

Be it known that we, Hilmar D. CURRraR and GEORGE R. EATON, citizens of the. United States, and residing at Chicago and -Oak Park, respectively. countyI of Cook and State of Illinois, have invented certain new and useful Improvements in Trunk Circuits, of which therfollowing is a specification.-

vOur invention relates to telephone systems and has to do more particularly with multi-otlice exchange systems in which the subscribers stations of the same exchange or different exchanges are connected by means of manual switchboard apparatus and autoand one of the main Obliects of our` invention is to provide improved circuit arrangements for a syst-em of the above character, and in which we eliminate the special B or trunking` operators.

In most multi-office exchange telephone systems of the above type, that is. wherein operators are provided for manipulating the cord and trunk circuits. the Operators use cord circuits for interconnecting the lines of their own exchange, but when they desire to connect with a line in a distant exchange, they connect to a trunk circuit terminating before a B or special trunking operator in the distant exchange. The .B operator connects the trunk circuit to the wanted line after having communicated with the A operator at the originatingl exchange over a special order wire independent of the trunk circuits. In the larger exchange systems even the calls local to an exchange are trunked to a B operator, who completes the connection. g

Systems of this character have been found t'aultv.l due to the fact that special trunking positions and trunking operators are required to handle these trunking connections, and to overcome these objections we provide circuits in which the A operator, in addition tothe usual answering and multiple jacks for establishing localrconnections. is provided with trunk jacks which are accessible from herposition and which are connected to apparatus that extends to different exchanges and terminates in plugs before A operators at such exchanges so that each operator has both outgoing and incoming trunks.

One of the features of our invent-ion is the termination of the outgoing trunk jacks in the banks of finder switch structures, so

that when a connection is established with an outgoing trunk jack for extending a conneet-ion to a distant exchange, one of the plurality of finder switches is caused to operate to seize thetrunk jack.

Another feature of our invention is the termination of the .incoming ends of the Vtrunk circuits at the distant exchanges in individual non-numerical trunk selecting switches, which trunk selecting switches are adapted to extend the connections to idle trunks leading to idle operators. at the distant exchanges.

A further-feature of our invention is the Iprovision of means for automatically busying all of the trunks terminating at .an operators position during the time that she is establishing a connection. A

These features, as well as others, will be more fully pointed out in the following description and appended claims.

For a more complete understanding of our invention reference may be had to the accompanying drawings, in which we illustrate apparatus for interconnecting two subscribers at diferent exchanges and which comprises Fig. 1, parts 1, 2 and 3, which, when joined, illustrate a complete connection. All the parts have been shown at normal and the apparatus shown in part 1 and the left-half of part 2 is located at one exchange, and the right half of part 2 and all of part 3 in another exchange.

Referring novvmore in general to the preferred form of our invention, it comprises exchanges M and N. At the exchange I, a plurality of substations A are provided, terminating in line circuits L comprising the usual cut-Off relay CO, line relay LR. multiple line lamps S and multiple jacks J. The multiple jacks J terminate before a number of different operators positions, each of which is provided with a line signal S so that when a call is initiated a plurality of signals S are lighted. and thus ai number of Operators are apprised of the call.y For sleeve relay ST which is energized-when an linterconnecting the substations a plurality answering plug AP is inserted into the jack J of a calling line. The relay ST is provided with a high and low resistance Winding, and upon the actuation of relay ST t-he high resistance winding is shunted and thus prevents a relay ST of another cord circuit, as B, frombeing energized, should the operator associated with the second cord attempt to answer the call. An operator of another cord attempting to seize the call after the first operator has connected to the calling line is prevented from communicating with the subscriber as the low winding of relay ST of the first cord prevents the relay ST of the second cord from operating. As the second operator is not connected to the calling line, due to the relay ST of the second cord remaining normal, she does not receive an answer from the calling subscriber and withdraws the answering plug of her cord circuit from the connected jack.

An answering supervisory relay AS is also provided and is actuated upon the energization of relay ST. The said relayv AS upon actuation prevents the premature light- 'F of the calling subscriber to restore to normal t-o permit the subscriber to recall. The relay LD also operates when the calling subscriber replaces his receiver and before the called subscriber answers to disconnect the ringing current rfrom the called line when the cord circuit B is used for establish! ing a local connection.

The calling end of the Acord circuit is provided with a sleeve relay SL actuated when the calling plug CP is inserted into a jack of the called local line or into an outgoing trunk jack which extends to a distant eX- change. The relay SL, upon energization, opens the circuit of the listening relay LS', which relay deenergizes to disconnect the operators set O from the cord conductors. A party line ringing key RK is provided for connecting one of a plurality of ringing generators G, G', G2, G3 and G4 to signal called subscribers when the cord circuit is used to establish a local connection. A ring-` which is actuated upon the response of the subscriber at the local called for substation. A supervisory relay SR is also pro vided which is actuated upon the response of the called for subscriber, either bythe response of a locally connectedlsubscriber or a subscriber at a distant exchange. A calling supervisory lamp CL is provided and is used for the usual supervisory purposes.

In order. to handle trunking connections in addition to the equipment just described, a trunk order wire key OW is provided for each cord circuit, which key when actuated operates a secondary listening relay SLR which connects the operators set O, and also opens the cord conductors. The operators set O is connected to the calling end of the cord circuit B, whereby the operator at the said cord circuit B may converse with the operator to whomthe trunk connection is to be extended.

The secondary listening relay SLR, the battery feed and tone disconnect relay BR and tone device ST are common to an operators position and are'brought into association with a trunking connection when the order wire key OW is actuated, as will beniore fully hereinafter described.

Referring now to part 2, we here show'a trunk jack .TJ of which there are a number, before each operators position, and which are multiply connected to a plurality of finder switches- FS whereby any one of a plurality of the said switches FS may seize the connected trunk jack TJ, as will be more fully hereinafter described. Associated with each trunk jack TJ we show a line relay LR and a cut-off relay CO', for purposes as will be more fully hereinafter described. The finder switch FS may be of any desired or suitable construction and is provided with a spring-restored shaft having wipers 2. 3, 4 and 5, and with four sets of fifty contacts 6. 7. 8 and 9, to which contacts the trunk jacks TJ are multiplied.

A rotary step-(by-step magnet RM is provided for rotating the switch shaft and wipers 2. 3, 4 and 5 by means of a ratchet and pawl mechanism. A retaining pawl is also provided and adapted tobe operated by a release relay RR for permit-ting the shaft wipers 2, 3.y 4 and 5 to be restored to normal bv springr tension. A common starting` wire Sl-V is provided and is common to a group of trunk jacks TJ which lead to a group of switches. A bridging relay BG is provided which energizes when the trunk jack TJ is seized by the switch to shunt the rotary magnet RM to prevent further advancement of the wipers 2, 3, 4 and 5. The switching relay SH energizes upon the actuation of relay BG to extend the starting conductor SW through to the next finder switch FS (not shown). The switch is also provided wipers remain'in 'contactwith the last-trunk used, and willagain seize the trunk last 1919, and

with a sa f tif-tm'rm 1v contacts 0N what assume their alternate posit-ion upon the first step of the sw-itch olf-normal andremain so until-the switch is again'restored to normal. For a more complete ,description of the switch ES, referencem'ay beh'adt'd ourco-A application filed February 24th,-

.bearing Serial No. 278,745. The trunking. circuit extends l'to the distantexchange 'via vthe conductors 11 and pending 12, -which conductors terminate in atrunking switch FS located at the said distant exchange N. I`he switch structure of FS 1s of an approved type of switch,k xiown as a switch yof the non-restoring type,' 'whose used,"provided the trunk inthe meantime `has not been seized for extending a cornice-' The switch- FSf is provided witha line relay LR, which relay LR?. actuates when the switch .FS seizes the i outgoing tion.

i trunlj jack TJ. A'set-of olf-normal contactsON are provided which assume their alternate positions upon thefenergization-of the, line 'relay LR?. -A rotaryjp'stepL-bystep -magnet-RM .is provided which-steps the -wipers 13,' 14, 15 tothe next-set of'contact's 16, '17 and 18, in case the contacts last en-'J gagedby the wipers 13, 1 4; andv 15 are busy,

and continues to do-soiuntil an idlefs't of contacts 16, 17 -and 18 areencountered lead-A- ing to an idle operator.' A cutoffrelay CO2`is provided which is energized when an f idle operator is seized and thefenergization' of rel'ayCO` restoresthe off-normal contacts O Nf. -The `toifnorn'ial springs are so arranged that when the linerelay LR2 energizes a '-.c'atch mechanism -is -'operated to. release the 0E- normal springs ON to their operatedv posit1on,and upon the energizevtion of thecut-oifrelay (JOf thesp'rings are restored to their normal,` position, inf-which position the catch,` mechanism is brought i into operation to hold the. off-.normal contactsNyin theirnormal position, AFor av v more detailed description o f. the switch tion iled- January 20th, 1919,-'and bearing Serial No- 271,960.

' windingsk a. b,

structure, reference 'may be hadto applica- Y The incoming'. trunk circuit C, as illustrated in Part 3, is adapted to be seizedby the switch FS and'tenninatesat-its incoming end in a repeating coil R(`J;-co mprising 'c and .d.- A high resistance test relayT is p when the .t'runk isl'seizedranda-relay SS is provided, which relay energizes upo'nf they energizationof the relay -T. A busy-relay BU is provided which islene'rgized uponthe ene-rgization of relay SS, ,the said relayBU busying all the other trunks termmating'at anoperators position 'while she is establishtrunk connection, as will be' more fully hereinafter described.A A listening relay provided rovided which is .actuated LS. common to the OperatorspOsitiOn is` energized uponthe energization of relay BU- toa connect the operators set Oto the trunk' conductors. A line lamp LL is prois li hted when relay SSopervided which ates to inform t e operator that 'ai-call is f awaiting her attention. A sleeve relay SL sertedin the jack lof the called line, busy guarding relay G U is also provided,

which relayGU is energized uponftheenwhich is energized when the trunk plug .TP of the trunkcircuit C isnf aling A ringing control relay4 C', a f

Vsringing.interrupter relay IR and a ringlng the-application .of ringing'current,fas will -jbe more fuuyqhereinafter described; A 'I callingsupervisory relay SR is also pro- -,vided which yisfenergized when the called subscriber.answers.v A busy relay BU is provided which is common to an operators position'and is energized when the o associa-ted wit-l1 the trunk circuit is establishing a local connection to busy her associated trunk jacks." .Thelistening relay rator LS of het' cord circuit is 4energized to close v Athe circuit'oi the busy 'relayv BU', which latter relay busiesthe trunks terminating'be-- fore her positi'on.l Whi'le establishing a, local connection. vv To...the right orl the drawing, we s howfavv called substation yD similar'to thesubstation' .ii

A, the said substation Dte'rminating at the exchange in a line -relay LR, cut-off relay. v CO3, multiple "jack J"- Having described'jin general the 'apparaline lamps S and jmultip'le.

tus used in establishing'a' connection between a -calling subscriber at -onefexcha'nge ,a and a called subscriber at another, we-will now describe in detail the operation 'of the apparatus in completing a" call freni the subscriber at substation-A of exchange M to' the subscriber at substation' D- at ex- .change N Assuming 'novi that the subscriber at' the "lllAV lao calling 'substation-A in the exchange -M thereat closes an energizing circuitfor the fline' relay LR of the line circuit L, over the '{line conductors'and the closing of the alterinitiates-a call', the removal'of the "receiver [nate contact-offline relay LR lights `line lamps S at a' plurality of operators posi-.

. tions.` Assuming that it is the'operatorassociated with the cord circuit B that answers the call, the insertion of the plug AP into the jack J of the callin line establishes a series energizing circuit 'or the cut-olf relay CO- of the line circuit L and the sleeve relay ST of cord circuit B over a circuit traced from battery through the windings 44 and 45 of the relay ST, conductor 41, closed contact 42`of disconnect rela LD, the sleeve contacts of the connectedI plug AP and jack J and through the winding of the cut-olf relay CO to ground. The closure of alternate contact 43 of relay ST closes a low resistance circuit through'the low resistance winding 44 of relay ST, the circuit being traced from battery through the winding 44 of relay ST, its alternate contact 43, over the previously traced path to ground at cut-olf relay CO. The high resistance winding 45 of relay ST is shunted, this arrangement providing for secret service,

as relay ST of a second cord will not operate in series with the relay C() for the reason that the low winding of the relay ST of the cord circuit B renders the relay ST of the second cord inoperative. The closing of alternate contact 46 of relay ST establishes an energizing circuit for the answerin supervisory relay AS traced from battery t rough the lower winding of the relay AS, conductor 47, normal contact 487 of relay LD, ring contacts of the connected plug AP and ack J, through the now closed contacts of the substation switchhook, back through the tip contacts of the jack J and plug AP, contact 49 of relay LD, conductor 50, through al-ternate contact 46 of relay ST,

l conductor 51 and through the upper winding nate contact 53 of relay AS to ground.

The opening of normal contact 52 of relay AS, upon its energization, prevents the premature lighting o the answering supervisory lamp AL. The energization of the relay CO of the line circuit L opens the energizing circuit of the line relay LR, which relay restores to efface the line signals The closing of alternate contact 53 of relay ST establishes an energizing circuit for the listening relay LS, the circuit being traced from battery through the winding of the relay LS, conductor 54, through alterof relay ST and conductor 55 to ground at normal contact 56 of the sleeve relay SL. The relay LS, upon energizing, closes its alternate contacts 57 and 58 to connect the operators set O to the cord conductors. Should another operator attempt to seize the call after the operator associated with the cord circuit B is connected thereto, the low resistance path through Winding 44 of the relay ST prevents the relay ST of the second cord from operating, and the listening relay LS of the second cord failing to operate does not connect its associated operators set O across the cord conductors. The second operator failing to receive a response, when she answers, knows ramoner that the call has been answered by another operator and withdraws the plug ot her cord circuit from the multiple jack of the calling line. l

The closing of alternate contact 59 of relay LS places a ground upon the conductor 60, which conductor leads to a busy relay common to a group of trunks which also terminate before the operator, the said relay actuating to place ground upon thel trunks associated with her position, busying them and preventing any of them being seized while she is establishing a local connection, as will be more clearly hereinafter described. The relay LS, upon cnergization, closes its lalternate contacts 57 and 58, connecting the, operators set (l to the cord conductors and the operator now inquires the wants of the calling subscriber at the substation A. vThe cord circuit B may beused for establishing local connections between the subscribers terminating at the exchange M. and also may be used for trunk connections between it and distant exchanges.

Assuming that the subscriber at the substation terminating at exchange M wishes to converse with a subscriber at the substation D terminating at the exchange N, the operator now inserts the calling plug Cl into a trunk jack TJ which leads to the exchange N, and after the insertion of the plug Cl into the trunk jack TJ, the operator actuates the trunk order wire key O V, which order wire key OW is individual to the cord circuit. The insertion of the plug CP into the trunk jack TJ establishes a series energizing circuit for the sleeve, relay SL of the cord circuit B, and the line relay LR associated with the trunk jack TJ, the circuit'being traced from battery through the winding ot the sleeve relay SL, conductor 61, sleeve contacts of the connected plug CP and trunk jack TJ through the winding of the relay LR t0 ground. Relay SL now energizes and opens its normal contact 56, thus opening the energizing circuit of the listening relay LS, which relay LS restores to normal. and the opening of alternate contact 57 and 58 disconnects the operators set 0 from the cord conductors. The closing of alternate contact 75 of relay SL closes a circuit for the calling supervisory lamp CL. traced from battery through the said lamp CL, normal contact 76 of relay RC, conductors 77 and 78, normal contac-t 79 of link disconnect relay LD, conductor 80` normal contact 81 of ringing trip relay RT, conductor 82. normal contact 83 of supervisory relay SR, conductors 84 and 85 to ground at alternate contact 475 of relay SL, said lamp CL now lighting.

The actuation of trunk order Wire key OW opens the cord conductors at the calling end of the cord circuit B at its contacts 62 and 63, and the closing of alternate conan energizing circuit -orthe secondary listening relay SLR over a circuit traced from battery throughthe Winding of said relay SLR, conductor 65 to ground at alternate Contact 64 of the key OW. The relay SLR, it is to be understood, is common to an operators' position. and the closure of its alternatecontacts 66 and 67 connects the operators set O to the calling end ofthe cord, over conductors 68 and 69, 70and 71 `and through make-before-break contactv 72 and 73 of the key OlV to the tip and sleeve conductors ot the cord circuits B. The closure of alternate contact 74 of the linerelay LR which is'associated with the jack TJ establishes an energizing circuit for the rotary magnet RM of the finder switch FS, associated with the trunk jack TJ, into which the calling plug OP ha'sbeen inserted. The circuit of the rotary magnet RM may be traced from battery\through the resistance 86. through the winding of the rotary magnet RM, its normal contact 87, conductor 88,'normal contact 89, of the off-normal contact ON, conductor 90, normal contact`91' of the switching relay SH,'the starting con-y ductor SW, which conductor SW is common to a group of trunk jacks TJ "terminating before an operators position, normal contact 92 of the cut-ott' relav CO to ground at alternate contact 74 of the line relay LR. Motor magnet RM upon energization steps the wipers 2, 3, 4 and 5 of the 'finder switch FS into engagement with the first set of contacts 6, 7, 8 and 9, and upon the first step of the wipers 2, 3. 4 and 5 from their normal position, the olf-normal contacts ON assume their alternate position, and the opening of normal contact 89 opens vthe initial energizing circuit of the rotary magnet RM. but a substitute energizing circuit is again established for the rotary magnet RM upon the closure of itsnormal contact 87, the circuit being traced `from `battery through the resistance 86. through the wind.

ing of rotary magnet RM, its normal contact l 87, alternate contact 89 of off-normal-contacts ON. normal contact93 of the switchin relay1 SH, conductor 94 to ground at norma contact- 95 of the bridging relay BG. The magnet RM, upon energization, steps the wipers 2. 3. 4 and 5 into engagement with the next set of contacts 6, 7, 84 and 9, and the opening of its normal contact 87 allows the magnet RM to restore; Upon, the

closure of' contact 87 magnet RM is againV -conductor 60" to the bus F-S having' selectedtrun Jack TJ to-be usedgf;

energized. and the interruption of its contact- 87 causes the said magnet RM to energize and deenergizc, stepping the Wipers 2, 4 and 5 over the contact sets 6, 7, 8 and 9. in search .of the elected trunk 'ack TJ, and when wiper 2 of the switch FS engages the grounded contact 6 associated with the trunk jack TJ of the elected trunk,`.a circuit is established for yrelay BG, traced from' RM, and the closing of make#before-break` Contact 106 of the relay BGcloses a locking circuit for thevrelay BG, tracel 'from ground at alternate contact 107 of theline relay4 LR', through the winding o f the cut-olf re.

lay OO', conductor 108, contact 7, wiper 3, conductor 109. through the lowerv Winding 11'0 of'relay BG, alternate contact' 106 of relay BG, through the upper windinglOB of 86 to battery and ground. The closing of alternate contact of relyBG establishes an energizing circuit fori e'switching .re-

suy

'the 'said relay, conductor 104 and resistance l'ay SH, traced from batterythroughthe winding of the saidfrelay SH, conductor mi t ground t *Imate @met Staffe-f lay' BG.

TheA closing ,oft/.alternate 11'2'off` relay SH establishes f locki Iom-` batterythiough' therwindingf .thai-relay SH, its' alternate.. contact f 112,9: conductor :113,1to

to yground at alternate-*.lfeontact ',114 .of oilnormal contacts" ON, f "Thefclosing off 'alteri j nate contact 91fiofwrelaySHjnow extends the common starting wire SW'; through the-said' alternate contact-91 tothe starting wireSW, which wire` SW- -'leadsto the-next s witchof the group lso'that in the-event an operator plug CP into a trunk jack -1' inserts another TJ associated Withher,A position',-thel` nent switch of the group willbe used t 'sejlect'the' trunk jack. The closing-fof alternate con#- tact 11,7 of' thesecondaryl listening relayV SLR' connnects the special l.tone ST to the tertiary' ,winding 121` of the operators 'set O, Vthe `tone 'being traced fromthe special tone apparatus ST to of relay SLR'conductor '118, normal contact v11'9 of relay' BR, conductor 120, through the alternate contact 117 v winding 121 offthe .operators inductionV coil L ICto ground.

ceives at-one notifying her that the switch The operator of the cord cir-4,

cuit B extending the-'trunk connection-'re--- i129 i FS is operating' to select the elected-trunk.

Closure of 'contact 59 connects in extending the connection vtothe distant exchange contacts BG closes its alternate grbund over relay. The switchr N, wipers 2, 3, 4 and 5 engagvftheA 6, 7. 8 and 9 l,associated with ,the trunk jack TJ and the 4energizationof"relaycontacts and116'v lio fait to close the continuity of the trunk conductors 11 and 12, which now extends the connection tothe incoming end at the distant exchange. rlhe ,trunk selected terminates' at the distant exchange N in a switch FS', and upon the closure of the alternate contacts 115 and 116 of the relay BG of the switch FS, an energizing circuit is established for the combined battery feed and tone disconnect relay BR associated with the cord circuit B at the originating exchange M and for the line relay LR? of lthe switch FS at the incoming end of the trunk at the exchange N.

The circuit of the relays BR and lLR2 may be traced from battery through the upper Winding 122 of line relay Lllz, conductor 123, normal contact 1% of the rotary magnet RM', conductor 125, normal contact 126 ot' the odnorrnal contacts 0N', conductor 127, Vnormal contact 128 of the cut-ott` relay C02, conductor 11, alternate cont-act 115 ol" the relay BG, Wiper 1, the contact 8, tip contacts of the connected plug and jack CP and TJ, make-betore-break contact T2 ot' the order wire key 0W, conductor 71, to ground through the winding 129 of the relay BR.-

A. second circuit is also established t'or the said relays and may be traced from battery through the Winding 130 of the relay l conductor 70, alternate contact T3 ofthe order Wire key 011V, ring contacts to the connected plug CP and trunk jack TJ, contact 9, Wiper 5, alternate contact 116 of the relay BG, trunk conductor 12, normal contact 131 of relay CO2, conductor 132, through the winding'133 of the line relay LRZ to ground at normal contact 131 of the oil'- normal contacts 0N. The relay BR, upon energization, opens its normal contact 119, disconnecting the tone ST from the operators set O of the cord circuit B, notifying her that the triuik jack TJ has been selected, and that the call has been extended to the distant exchange N.

The switch FS', as already stated, is of the non-restoring type., and should the Wipers 13, 14, 15 be resting on an idle set ot contacts 16, 17 and 18 leading to an idle operator at the distant exchange, the switch F S remains in engagement With `the said contacts last used Without any actuation ot the switch. Should the contact 16` which We may term a test contact be grounded, due to the operator with which the trunk C is associated being busy in establishing a local connection or a trunk connection. the contacts 16 Will have a busy or ground potential thereon. The line relay LRZ, upon energization, holds the off-normal contacts 0N in their alternate position and, assuming that the operator associated with the trunk C is busy, upon the closure of alternate contact 135 of the relay LRZ, an energizing circuit for the rotary magnet RM is established,

stitute circuit is traced from battery through the winding of the said magnet RM', conductor 136,- alternate contact 135 of relay LR2, conductors 137 and 138, Wiper 13 to the engaged grounded Contact 16. The line relay LRZ has its circuit opened when off-normal contacts 0N assume their alternate position, at which time normal contact 126 moves to its alternate position, but asubstitute circuit is established for it, which may be traced from the grounded busy contact 16,

wiper 13, conductor 138, normal contact 139 the rotary magnet RM steps the Wipers 13,

14 and 15 from one contact set 16, 1? and 18 to the next until the idle contact 16 leading to an idle operator is encountered, and as this idle contact 16 is free from ground, relay LRZ and magnet RM remain at normal. preventing further movement of the switch Wipers 13, 11 and 15. lllhen an idle set of contacts are encountered, a circuit for cutoft1 relay CO2 of the trunk switch FS is established` traced from battery through the winding of the cut-oil' relay @02, conductor 141, normal contact 1412 of rotary magnet RM', conductor 143 to ground at alternate contact 134 of off-normal contacts ON. The relay CO2, upon energization, restores the olf-normal contacts ON to their normal position and the opening of alternate contact 134. interrupts ther initial energizing Circuit for the cut-oill relay C02, but a subestablished for the said rellt) lay G02, as will presently be described The contacts 128 and 131 of relay CO2, upon energization, assume their alternate positions and open the circ-uit of relay LRE. It the Wiper 13 of switch FS is engaging an idle Contact 16 free from groundwhen the call is extended to switch FS', no circuit is established for rotary magnet RM and a circuit is immediately established for cutoff relay CO2, which relay upon energ'ization opens the circuit for relay LRQ at its contacts 128 and 131 and brings about thc restoration of the olf-normal contacts ON. The Wipers 13, 14 and 15 having engaged a set of contacts 16, 17 and 18 leading to an idle trunk circuit C and the closure of altern'ate contacts 128 and 131 ot' the cnt-oft relay CO2 extends the trunk conductors to the of the trunk circuit C is now eStabliShed, traced.' from battery through the winding lay BU, conductor 157,

-coil' RC, conductors the' winding of the relay 'Tfconductcrs 152 I and'153, the' winding bv of the repeating of the connected plug ,TJ, alternate contact-72 of the order Wire:

OW, conductor 71l to ground through-- winding 129 of the' relay BR.A The closing'- of alternate contact 154 of the relay T-estab'- ondary relay through the gizing circuit for the 7 relay SS placesa ground upon thetest 13 0 ofthe relay BR associated with cord B at exchange M, conductor 70, alternate contact 7 3 0f the order Wire key OW, ring contacts ofthe connected plug 'CP and trunkv ;jack, TJ, contact9, Wiper 5,- alternate con# tact 116 'of relayrv BG, trunkj conducto'1f-12, -alternate contact 131 of relay CO2, wiper "15, 0,7" ofxthefrepeating contact '18, winding 150 and2151, through lcoil RC, contact 17, wiper 14 of tmnk'switch FS', alternate contact 128 of the relay CO2.

trunk conductor the relay BG, Wiper 4,

lishes an energizing circuit for the sec- 'The closure of alternate contact.1 80. of the con- - tacts 16 of the trunk switches FS,\. With inultipledfeyenting. trunks from `ing select tending' theffconnection tothe calledsu vscriber at the'subeittion D.: Wefalsorshowt- 's' particular'trunk cir-cuitfC that also closesva relay C. from" groanatalternate contaarlof re duringjth'e time that 'sheis ex connection; When 11, alternate contact 115 of contact 8, tip contact CP and trunk; jack?l SS, traced from'. battery winding of the relay SS, lcon-g. ducto; 155 togro'u'nd' at alternate contact:

trunk is multiply associated,' vpreventin'gnfany other trunk switch from l selecting t is nowA in' use m extending the connect-ion tothe subscriberat substation D.- Thisground locking circuit for thecut-o ff 'oijthetrunk' switch FS', tnnl'tGtht-a call has 'been extended to lier'` B U, which relay is f common to an operators' positionand isf fencrgizedf5l i when the operator is lestablishing a rthe--lngh i191 used, the listening 1 L Sfof tl1 e ;cord

closes its alternate contact 59, which fe'stzrxbf` lishcs'an energizing' clrcuit for thelinsy relay BU from ground at alternatezlm'xitact 59 of the listening relay LS ofthe cuit `jthat' isin establishin' alocalconnection to battery andl groun through the winding of relay BU. The closure of alter this operators position, the ground extendingjo the test' contacts 16-offthe trunk smtchesfFS 'to'fwhich the trunks are multipled', preventing -ythel said' switches from i nfeontacts 189,-Af'1'90,f1 91 and- 192 connects ground to the trunkA circuits terminating 'at sewingany trunkterminating'at thislop'- erators lposition whileshe is establishinga' 'vlsfaisi'establis'hed upon the closuref'o alter? i naterif'cciltact. 156,- fraced frame bai-,wry

will be more after described.' Theclosure of alternate contacl ,161'and 162 ofthe relay BU VestabenergizingA circuit for the .listeningrelay voverthe conductors 163 and 164 throughscribed' path, v including windings 129 and 130 of the-relaylv BR. The closure of alternate contacts' 167 and v168 of the listening relay LS thetrunk conductors, placing the operator ofjthetrunk circuit C.

with the operator of the ,cordcircuit' B at the exchange MM contact 17 6' of relay SSestablishes a circuit lfor the vline lam `the said lamr normal contact 177 of re1- layf GU, conduftors17E-and 179 to ground at ate Contact 176,-" The lar'npLL light-5 'the operator; associated with the l 1.- I n.,

ratorfof the trunk now qulr'eathe'number-of the operator. at-the excu'itftraced from battery throughthe lower lternate 'contacts 161 vand 162` of therelayV BU, over' conductorsl, 166 to battery. and' ground over the previously .de-

communication The closure of' alternate 8 0 locllconnection.' A- circ-uit for the relay A16(1- ully: herei-nconnects the operators set O to from battery through.

ius

mal contact 171 ot the ringing interrupter relay lll, normal contact 63 of order Wire key OW, contacts ot the connected plug CP and trunk jack TJ, contact 9, 1wiper 5, alter'- nate contact 1.16 of relay BG, trunk conductor 12, alternate Contact 131 of relay (CU2, wiper 15, contact 18, Winding a ot the repeating coil RC, conductors 150 and 151, through the winding of the relay T. conductors 152 and 153, winding L ot the repeating coil RC, Contact 17, wiper 141, alternate contact 128 of relay C02, trunlt` conductor 11, alternate Contact 115 ot relay BG, wiper 4, contact 8. tip contacts ot the connected trunk jack TJ and plug UP, normal contact (S2 ot' the order wire lacy (11V, nor mal Contact 172 of the ring interi-tiptel' relay ll?. of the cord circuit B, conductor 178, al= tcrnate contact 174 of the sleeve relay Sl.; to ground. through the upper Winding ot the supervisory relay Sll. The high resistance test relay rl prevents the energizatiou of the supervisory relay Slt, and the calling supevisolv lamp (lL of the cord circuit l5 at the exchange hl remains lighted until .the called subscriber D at the distant exchange N answers in response to his call signal. The..

operator of the truuk circuit C tests the line of the call subscriber B as to its idle 'Tir busy condition in the usual manner by placing the tip ot' the trunk plug TP to the sleeve' of the jack J' of the called line, and if the said line is busy, the operator receives thecustomary click in her head receiver, notifying her of the busy condition ot the called subscriber at the substation l). Assuming that the line is idle, the operator inserts the trunk plug TP into' the jack J' of the called line, and the insertion of the said plug TP establishes a series energizing circuit for the sleeve relay Sli and the cut-oli' relay CO3 ot the line circuit L', the circuit being traced from battery through the winding of the sleeve relay SL', conductor 175, sleeve contacts of the connected plug TP and jack J' to ground through the winding of the cut-olin relay C0". A

The sleeve relay SL upon energization closes its alternate contact 200, establishing an energizing circuit for the busy guard relay GU. traced from battery through the winding 201 ot the said relay GU,normal Contact 202 of relay GU, conductor 203, alternate contact 204 ofrelay SS, conductors 205 and 206 to ground at alternate contact 200 of the sleeve relay SL'. A locking circuit is closed throughl the lower winding 206 of the relay GU upon the energizing of the said relay GU, the locking circuit being traced from battery through the lower winding 206 of relay 1U. alternate contact 177 of relay GU, con# ductors 178 and 179 to ground at alternate Contact 116 ot the relay SS. A locking circuit is also established through the upper assurer winding 201 of the relay GU, traced from battery through the upper Winding 201, alternate contact 207 ot relay GU, conducf tors 205 and 206 to ground at alternate contact 200 of relay SL', and these two ,locking circuits `for the relay GU as just traced are for purposes as will be presently described. The opening of normal contact 177 ot relay GU opens the circuit of the line lamp LL, bringing about the effacement of said lamp LL. The opening of normal contact 158 of the sleeve relay SL' opens the energizing circuit of the busy relay BU, which relay opens its alternate contacts 183, 184i and 185 to remove ground from the conductors 185, 186 and 187, which conductors lead to the multiple test contacts 16 ot the trunk switches F S', rendering the remaining trunks at her position selectable, as the operator has extended the connec- `to the called subscriber and is now free to receive other trunk connections, pro- 1riding she is net now establishing local connections, and it she is thus occupied, the trunlrs are rendered busy in a manner as previously described. The closure of `alternate contact 208 of the relay GU closes ai? energizing circuit for the meter rela MR, traced trom battery, through the Win ing ot the meter relay MR, conductor 209, normal Contact 210 or' meter cut-clit relay MO to ground at alternate contact 208 of relay` GU, the said meter relay MR new actuating to register a connection. Illhe closure of alternate contact 208 et the relay GU also energizcs the meter cutoff relay M0, the circuit being traced from battery through the Winding ot relay MG to ground at alternate Contact 208 of relay GU. Themeter relay MO, upon energizing, opens its normal contact 210, preventing further actuations of the meter magnet MR, which meter mag# net MR nou7 restores to normal. A circuit for the ringing lamp RL is also established, traced from battery through the 'lamp RL, normal contact 216 of relay RC', conductor 217, normal contact 218 of ringing trip relay R'l", conductor 219, normal contact 214 of relay 215, conductors 205 and 206 to ound at alternate contact 200 of relay gli', and the ringing4 lamp RL is thus lighted, giving the operator of trunk C a visual indication notifyin her that the called subscriber at substation D has as yet not been signaled. To signal the called for subscriber at substation D, the operator associated with the trunk circuit Chow depresses the roper ringing key plunger of the ringing ey RK' to connect the proper ringing frequency from the generators G, G, G7 or Gs, as the case may be, to o erate the call signal of the Icalled subseri r at the substation l).I

Assuming that it is the generator G that is the selected frequency for signaling, she

l depresses the key plunger of the ringing key RK' associated with the said frequency, and the depression of the said key plunger actuates the end spring contact 211, causing it. to momentarily assume its alternate position, and the closure of the said alternate contact 211 established an energizing circuit for the ringing control relay RC',`traced from battery throughthe winding of the said relay RC', conductor 212, alternate contact 211 of the end Aspring ofthe ringing key R-K', conductor 213, normal contact 214 of the relay 215, conductors 205 and 206 to ground at alternate Contact 200 of the sleeve relay SL'. The closing of alternate contact 220 of relay RC' establishes a locking circuit for the said relay RC', traced from battery through the winding of said relay RC', its-alternate contact 220, conductor 217, normal contact 218 of ringing trip relay RT', conductor 219, normal contact 214 *of relay 215, conductors 205 and 206 to ground at alternate contact 200 ofthe sleeve relay SL', and the opening of normal contact 216 of relay RC' opens the circuit of the ringing lamp RL. )The closure of alternate contact 01 of the"v relay RC' closes an energizing p circuit for the interrupter relay IR', traced from battery through the Winding of the relay IR', conductor4 222, alternate contact 221 of relay RC', conductor'223, alternate contact 2240i relay SS, conductor 225 and through the constantly rotating interrupter I' to ground. The relay IR' is thus intermittently energized and de-energized by the interrupter I', and the ringing current `from generator G is thus connected and disconnected to intermittently operate the call signal at the calledfor substation D. The ringin current may be traced from the 11n- 'groun' ed pole of the generator G6, through the closed key plunger. contact of the rin ing key RK', conductors.y 226 and 22%, through the winding of the ringing trip relay RT', conductors 228 ands229, alternate contact 230 of the interrupter relay IR', the

' tip contacts ofthe connected trunk plug TP and jack J', through the condenser an call signal' at the called substation D, back through .the ring contacts of the connected jack J' and plug TP, to battery and groun through alternate contact 231 of the ringing interrupter relay-IR'. -The call signal at substation D is thus intermittently energized due to the intermittent energization and de-energizat-ion of the interrupter relay IR', a-nd the subscriber at substation D, in

err

response to his call signal, removes his receiver from the switchhook Should the said subscriber at substation Drremove his receiver during a ringing or live perlod, the combined generator and.: battery. flow through the Wind-ingof the ringing trip relay RT' causes the .same to actuate, and the opening of its normal cont-act 218 opens the locking circuit of the ringing control relay RC', which relay RC' restores, and the opening of its alternate contact 221 dis.- connects the interrupter I' from the interrupter relay IR', the said -relay IR' now restoring to normal and preventing further application of ringing current after the called subscriber at substation D answers in tact 231 of relay IR', ring contacts ofthe connected plug TP and jack J', through the now closed contacts at the substation switchhook at substation D, back through the tip contacts of the connected jack J' and plug TP, normal contact 230 of relay IR',` alternate contact 240 of the sleeve relay SL', Winding c of the repeating coil RC, conductor 241,- through the upperwinding of the relay SR' to ground.

The closure of alternate contact 242 of the relay SR', upon its energization, establishes an energizing circuit for the relay 215, traced from battery through the winding of the relay 215, alternate contact 242 of the relay SR', conductors 243, 205 and 206 toground at alternate contact 200 of the sleeve relay SL'. Relay 215, upon energizing, opens its normal contact 214 to open the locking circuit of the ringing controlrelay/ RC'. In this' way, in the event-that the subscriber D 'answers during a silent period, the said relay RC', upon restoration, opens its alternate contact 221, disconnecting the n- -through thelwinding of the said relay 215,

its alternate contact 244, conductors 205 and d 206 to ground at alternate contact 200 of relay SL'. The closing of alternate contact 245 of the supervisory relay SR', places a shunt about the high resistance winding of the testrelay T, and the circuit of the supervisory relay SR of the cord circuit B at the exchange M now extends over conductor 150, to alternate Contact 245 of relay SR', conductor 246, `throughlthe lower winding of the relay T, which winding is of lowa resistance, conductors-152 and 153 andA over the previously describedpath to the relay SR at the exchange M. The relay SR of the cord circuit B at the exchange M now energizes dueto the shunt about the high winding of relay T of trunk C at exchange N, and the opening of its normal contact 83 opens the circuit of the calling supervisory lamp CL, bringing about the effacement of the said lamp CL and notifying the operator of the cord circuit B at the exchange M that the called subscriber at the substation D at the exchange N has answered. The subscriber at the substation A at the exchange M and the subscriber at the substation D at the exchange N are now in conversational circuit, and the talking circuit may now be tnaced over the heavily marked conductors.

Assuming that the subscribers have finished conversation, they replace their receivers upon their respective switchhooks. The replacing of the receiver by the subscriber at the substation A of the exchange M opens the circuit of the sleeve supervisory relay AS of the cord circuit B and the closing of its normal contact 52 establishes an energizing circuit for the disconnect relay LD, traced from battery through the winding of the relay LD, normal contact 52l of relay AS, alternate contact 250 of relay ST, conductor 85 to ground at alternate contact 75 of sleeve lrelay SL. The link distconnect relay energizing disassociates the calling line from the strands of the cord circuit at its normal contacts 48 and 49 and closes alocking circuit for the relay ST extending from battery through the said relay, its alternate contact 43, conductor 41, alternate contact 42 of relay LD, alternate contact 250 of relay ST to ground at alternate contact 75 of relay SL. The relays LD and ST remain energized until the connection is taken down. The open.- ing of normal contacts 48 and 49 of relay LD allows the cut-ofi' relay CO of the line circuit L to restore, which places the line circuit L at normal.

The closing of normal contact 52 of relay AS closes a circuit for the answering supervisory lamp AL, traced from battery through the lamp AL, normal contact 52 of relay AS, alternate contact 250 of relay ST, conductor 85 to ground at alternate contact 75 of relay SL. The answering supervisory lamp AL is lighted, notifying the operator that the subscriber at the calling substation A has replaced his receiver upon the switchhook. The subscriber at substation A may immediately initiate a recall before the answering and calling plugs AP.

and CP are removed, by again removing his receiver'which agaln brlngs about the energi'zationof the line Arelay LR, which relay,

upon energization, closes the circuit for the .multiple line lamps S, and the same operator Yor another operator mayseizethe recall.

' The subscriber ofthe substation D at the distant exchange N 'now places hist receiver -upon the switchhook to openthe energizing circuit of the supervisory relay SR' of the trunk circuit C. Upon the restoration of the relay SR, its alternate contact 245 is again opened, removing the shunt from about the high resistance winding of test relay T, and the circuit of t-he supervisory relay SR of the. cord circuit B at the exchange M again extends through the wind-l ing of the high resistance test relay T, and the circuit through the relay T of the trunk circuit C of exchange N allows relay SR of cord circuit B to restore, due to the high resistance of the test relay T, and the closure of its normal contact 83 again closes a circuit through the supervisory lamp CL., notifying the operator at the exchange M that the called subscriber at the substation D at ,the exchange N has replaced his receiver. The operator at the exchange M, noting the two lighted supervisory signals AL and CL, removes the answering plug AP from the jack J and the calling plug CP from the trunk jack TJ. The removal of the plug CP from the trunk jack TJ opens the energizing circuit of the line relay LR associated with the trunk jack TJ and the sleeve relay SL of the cord circuit `B of exchange M, and the line relay LR', upon restoration,

opens its alternate contact 107, `opening the closes its normal contact 95, closing an energizing circuit for the release relay RR of the said switch F S, the circuit of the release relay RR vbeing traced from battery through the winding of relay RR, alternate contact 93 of relay SH, conductor 94 Vto ground at normal contact 95 from relay BG. The release relay RR, upon energization, re moves the retaining pawl from the ratchet, allowing the wipers 2,3, 4 and 5 to restore to their normal position under spring tension, and when the wipers have restored tonormal, olii-normal contacts ON are moved to again assume their normal position, and the opening of alternate contact 114 of offnormal contact ON opens the locking circuit of the switching relay. SH, which relay SH,restores to normal, and the opening of alternate contact 93 of said relay SH opens the circuit of the release relay-RR, which relay RR also restores. The finder switch FS is now at normal andis available for extending other trunk connections.

The removal of the .plug CP from the Y 154, which brings about thel restoration of the relay SS. The relay SS, upon cle-ener- .gization, opens its alternate contact 176 and opens the locking circuitthrough the llower i 1,556,7ei

winding 206 of the relay GU, but the relay GU does not restore at this time due to the locking circuit through the upper winding 201 to ground at alternate 'c0ntact`200 of nated. The o ening of alternate Contact 156" of the relay S allows the relay `160to restore= and the opening of alternate contact 180 4of the relay SS permits the de-energization of the cut-olf relay CO2 of the trunkA switch FS. Therelay 160 is made slow to release so that whenv its `ener ing circuit is opened, its contact 272 is hel momentarily open due to its slow to release construction, permitting the said cut-off relay CO2 to fully (le-energize. The relay CO2` u on restoration places the switch FS in condition to be usedv for selecting purposes. Ihe operator at the trunk circuit C -having as yet not withdrawn the plug TP from the jack J', the locking circuit through the upper winding 201 of the relay GU is still maintained, and the closing of normal contact 272 ofthe relay 1 60 now places a ground upon the test conductor 182 which leads to the test contacts 16 of the trunk switch FS to which the trunk circuit C is multipled, the ground extending from ground at alternate contact 273 of relay GU over conductor 27 4, normal contact 272 of relay 160, conductors 181 and 182 to the test -contact 16. The ground from the said alter,-l nate contact`273 places a ground or busy potential upon the test contact 16, thus preventing any other finder Switch FS` from selecting the trunk circuit C Vthat is still connected to the called line D. The operator noting the lighted disconnect lamp DL, knows that the operator at the'exchange M has withdrawn .the plugs of the cord circuit B from the respective jacks and she now withdraws the trunk plug TP from the jack J of the called line. The removal of the plug TP opens -the series energizing circuit for the sleeve relay SL", and thecut-ofi' relay CO3 and the opening of alternate con-` tact 200 opens the locking circuit through the winding 201 of the relay GU, and the openingof the said alternate contact 200 of sleeve relay SL also opens the locking circuit of the relay 215. The opening of alternate contact 270 of the sleeve relay SL brings about the effacement of the disconnect lamp DL. The relay GU upon de-energization opens its alternate contact 273, removing ground from-the test conductor 182 which extends to the test contacts 16, thus removing the busy potential of the said contacts 16, now rendering the trunkv circuit C at the exchange Jselectable by other trunk switches F S. The opening of alternatev contact 208 opens the circuit of the meter cutolf relay MO, the. said relay MO restoring to normal. The apparatus that was used in establishing the connection from the calling subscriber at the substationQA at. the exf change M to the called subscriber D at the exchange N is-now at normal and available for. establishing other connections.

lvhile we have illustrated and described a specific form of our invention, we do not wish to be limited to the same, as changes andmodiicationswill readily suggest themselves to those skilled in the art, and we, thereore, aim to cover all such lchanges and v modifications as come within the spirit. and

.scope of the appended claims.

`What we claim as new and desire to se- `cure by United States Letters Patent, is:

1. A telephone system including a plurality of outgoing trunk jack terminals, a pluralityv of incoming trunky plug terminals, finder switches and non-preselecting nonrestoring trunk switches intermediate said Outgoing jack and incoming trunk plug terminals, manually operated cord circuits having connection terminals', and means for operating one of said finder switches and one of said trunk switches when connection is made by one of said manually operated cord circuits with one of said outgoing trunk )ack terminals to connect one of said out- .going trunk jack terminals to one of said incoming trunk plug terminals.

2. A telephone system including an outgoing trunk jack terminal and an incoming trunk plug terminal, apair of non-numerical non-preselecting trunking switchesintermediate said terminals, a manually op- -erated lcord circuit having connection terminals, and means for causing an operation of said non-numerical non-preselecting switches when connection is made by said cord circuits with said outgoing trunk jack terminal to connect said outgoing trunk jack terminals to said incoming trunk plug terminal.

4. A telephone system including an outllO for causing the operation of said switch when connection is made wit-l1 said outgoing trunk jack terminal, to connect said outgoing trunk jack terminal to said incoming trunk plug terminal via a set of said bank contacts and said contactwipers, said contact wipers remaining in engagement with the set of bank contacts last engaged when said connection is taken down.

5. A telephone system including an outgoing trunk jack terminal appearing before an operators position at an exchange and a plurality of incoming trunk plug terminals terminating at a distant exchange, a subscribers telephone line, an operator-"s cord circuit for said' operator-s position for interconnecting said line and said trunk jack terminal, a ,non-numerical non-restoring switch, said switch being adapted when said outgoing trunk jack terminal is seized upon the connection of said cord circuit with said 'trunk jack terminal to connect said outgoing trunk jack terminal to the incoming trunk plug terminal on which the wipers of said switch are resting if said incoming trunk plug terminal is idle, and automatic means controlled over said subscribers line for freeing said subscribers line from said cord circuit without affecting the said switches.

6. A telephone system including an outgoing trunk jack terminal and an incoming trunk plug terminal, a. subscribers tele- Phone line, an operator-Fs cord circuit for in-A terconnecting said telephone line and said trunk jack terminal, a finder switch and a non-numerical non-preselecting and non-restoring trunking switch tied tail to tail intermediate said trunk terminals, means 'for operating said switches to connect said outgoing trunk jack terminal to said incoming trunk plug terminal, and means for said cord circuit for freeing said line from said cord circuit without a'ect-ing the operation of said switch,

' 7. A telephone system including subscribers telephone lines, a plurality of outgoing trunk jack terminals appearing before operators positions at an exchange, link circuits for said operators positions for interconnecting the subscribers telephone lines and said trunk jack terminals, a plurality of incoming trunk plug terminals terminating in an operators position at a distant exchange, pairs of non-numerical automatic switches intermediate said outgoing jack and said incoming plug trunk terminals, means responsive to the connections of a link circuit at said first exchange to one of said trunk jack terminals to cause an idle pair of said switches to connect said outgoing trunk jack terminals to an idle one ofv said incoming trunk plug terminals at said distant exchange, and means at said first exchange for permitting the operator thereat to converse with the operator at the distant exchange over the conductors of the trunk circuit controlledby said pair of switches.

8. A telephone system including a multiexchange telephone system including a plurality of outgoing trunk jack terminals extending towards each of the exchanges in the system, a plurality of incoming trunk plug terminals at each exchange accessible :t'roml the other exchanges, trunk circuits extending between each of said exchanges terminating at their opposite ends in non-numerical non-preselecting trunking switches, the said switches terminating in the trunk plug terminals being also non-restoring, and means for setting in operation a non-numerical switch of one of said trunk circuits associated `with an outgoing jack terminal to connect said trunk circuit to said outgoing jack terminal when connection is made with an outgoing trunk jack terminal and for setting in operation a non-numerical switch associated with the opposite end of said trunk circuit at another of said exchanges to connect said trunk circuit to an idle one of said incoming trunk plug terminals at. said latter exchange.

9. A telephone system including two telephone exchanges, outgoing trunk jack terminals at one of said exchanges and incoming trunk plug' terminals at the other of said exchanges, trunks extending between said exchanges and terminating in their opposite ends in non-numerical non-preselecting trunking switches, the said switches at the incoming trunk plug terminals being a1- so non-restoring, and means for setting in operation one ot' said non-numerical switches at the rst of said exchanges when connection is made with one of said out-going trunk jack terminals to connectone of said trunk circuits to one of said outgoing trunk jack terminals and for setting in operation the switch associated with the other end of said trunk circuit at the other exchange to connect said trunk circuit to one of said incoming trunk plug terminals at said other exchange.v

10. A telephone system comprising telephone lines terminating at operators positions in different exchanges, subscribers cord circuits at each of said positions, trunk circuits, outgoing terminals at each opera-' tors position and incoming terminals at the operators positions in the other exchanges whereby each operators position may be connected over said trunks to operators no sitions in the other exchanges, non-numerical automatic switches for connecting the V connected over' said trunks to operators positions in the other exchanges, non-numerical automatic switches `for connecting the outgoing and incoming terminals of said trunk circuits. .and a common relay associated with each operators position for rendering the incoming trunk circuits associated with her position busy.

12. A telephone systemvcomprising telephone lines terminating at operators positions in diiierent exchanges. subscribers cord circuits at each of said positions, trunk circuits, outgoingl terminals at each operators position and incoming terminals at they op- -erators positions in the other exchanges whereby each operators position may. be

connected over said trunks to operators positions in the other exchanges, non-numerical automatic switches for connecting' the said outgoing and incoming terminals of'l trunk circuits, an operators busy relay, connections extending from said relay toeach 'of the incoming trunk terminals at an operators position, and means including said connections whereby when 'a call isbeing answered at said operators position said, relay is operated to render all of said incoming trunk terminals busy.

13. A telephone system comprising `telephone lines terminating in different exchanges, link circuits at each of said exchanges, trunk circi'iits, outgoing terminals for said trunk circuits at said exchangesyin'- coming trunk terminals for said trunk 'circuits at said exchanges, non-numerical automatic switches for connecting saidbutgoing trunk terminals to said incoming trunk terminals, and control circuits whereby when a call is extended to an operators position of one of said exchanges all the trunks leading from said operators position of said exchange are rendered inaccessible.

14. A. telephone system including telephonev lines yterminating at different exchanges, linkcircuits at each of said exchanges, trunk circuits adapted to be extended rom one of said exchanges to each of the other of said exchanges, incoming and outgoing terminals for said trunk circuits, means including one of said link circuits,

an outgoing trunk'terminal, an automatic switch and an incomin trunk terminal for extending a call rom a subscribers line of one of said exchanges to a subscribers line of another of said exchanges, means responsive to the extension of said connection for connec lthe opcoming trunk terminal `to the said linkv circuit and for rendering all the incoming trunk. terminals associated with the operators telephone inaccessible.

,15. A telephone system comprising telephone lines terminating at operators positions differentexchanges, subscribers cord circuits at each of such positions, trunk jacks accessible from each of said positions and having outgoing trunk circuits, incom- Aerators telephone ,associated wit thev inc ing trunk circuits at each operators posi-A tion in' the different exchanges, non-numerical automatic switches intermediate of said y outgoing and incoming circuits terminating at connecting plugs at A'or subscribers operators positions in all of lthe other exchanges whereby each subscribers operator may etlect connection between telephone lines accessible from lier position or may extend connections from calling lines accessible from her position through said subscribers cord'circuits .and said trunk circuits to operators positions at distant switchboards through the agency of said switches, and a. common relay associated with each operatorsposition for rendering the incoming trunk circuits associated with her position busy. l,

16.,A telephone system comprising telephone lines terminating at operators positions, subscribers cord circuits at each of such positions, trunk jacks having outgoing trunks extending from each operators posi- *tion lto plug terminals at other operators positions whereby each operators position as both iackand plug terminals of outgoing and incoming trunks at hei' position, non-numerical automatic switches for' oonnecting the outgoing and incoming terminals of ,said trunk circuit, said cord and trunk circuits having control circuits whereby each operator may effect connection be tween telephone lines accessible from her position by said cord connections ffrom calling lines accessible from her tion through said `subscribers cord circuit and said 'trunk circuits to operatos at distant positions, through the agency of said 'non-numerical automatic switches` and means associated with the distant ends of the trunk circuit extending from an operators position toa distant exchange for rendering all incoming trunk circuits at the said distanty exchange busy. v

17. A telephone system comprising telephone lines terminating :it-operators sitions in di'erent exchanges, subscri rs cord circuits at each of such positions, trunk circuits or may extend jacks having outgoing trunks extending from each operators position to plug terminals at other operators positions whereby each operators position has both jack and plug terminals and outgoing and incoming trunks at her position, non-numerical automatic switches for connecting the outgoing and incoming terminals of said trunks between different exchanges, and control circuits for rendering inaccessible the incoming trunks of an operators position whenever a call is being answered at her position from a telephone line or from an incoming trunk at her position.

18. A telephone system comprising telephone lines terminating at operators positions in different exchanges. subscribers cord circuits at each of said positions, trunk circuits, outgoing terminals at each operators position for such circuits terminating at incoming terminals at operators positions in the other exchanges, and non-numerical automatic switches for connecting` the outgoing and incoming terminals of said trunks between different exchanges. whereby each operators position ma)v be connected over said trunks to operators positions in other exchanges, and busying means for rendering inaccessible all incoming trunks at an operators position'when said operator is answering a call at her position from a telephone line or from an incoming trunk.'

19. A tele-phone system comprising telephone lines terminating at operators positions in ditl'erent exchanges, subscribers cord circuits at each of said positions, trunk circuits, outgoing terminals at each operatorsposition for such circuits terminating at incoming terminals at operators positions in the other exchanges whereby each operators position maybe connected over said trunks to operators positions in other exchanges, non-numerical automatic switches for connecting the outgoing and incoming terminals of said trunks between exchanges, busying means for rendering inaccessible all incoming trunks at an operators position when said operator is answering a call at her position from a telephone line or an incoming trunk, and means for rendering the busy signals at all but the used trunks leading to her position ineffective upon extending an answered call. I

20. A telephone system comprising telephone lines, terminating in different exchanges, link circuits at each of saidexchanges` incoming and outgoing trunk circuits extending from one of said exchanges to each of the other of saidexchanges, nonnumerical automatic switches for intercor'xnecting said incoming and outgoing termlnals of said trunks between exchanges, busyin signal means associated with each of sald trunk circuits, and control circuitsv whereby when an operator is answering a local call at one of said exchanges all the trunks leading to her position will be rendered busy.

21. A telephone system comprising telephone lines terminating in different exchanges, l'ink circuits at each of said exchanges, incoming and outgoing trunk circuits extending from one of said exchanges to each of the other of said exchanges. nonnumerical automatic switches for interconnecting said incoming and outgoing terminals of said trunks between exchanges, busying means associated with each of said trunk circuits. and control circuits' whereby when a call is extended to one of said exchanges all idle trunks leading to the coming terminals of said trunks between v different exchanges. means including one of said link circuits and an outgoing trunk circuit for extending a call from a subscribers line of one of said exchanges to a subscribers line of another of said exchanges through the agency of said switches, and means responsive to the connection of said link to said trunk circuit for connecting the operators telephone associated with the said trunk'circuit to the said link cir-- Cuit and for causing all of the incoming trunk circuits associated with the opera-' tors telephone to indicate busy.

23. A telephone system comprising subscribers lines terminating at operators positions in different exchanges. link circuits at each of said positions. trunk lines extending from one of said exchanges to each of the other of said exchanges, outgoing and incoming terminals for each of said` trunk lines, non-numerical automatic switches for connecting` the outgoing and incoming terminals of'said trunks between different exchanges. means includingr the said link circuits whereby each subscribers operator may effect connection between lines associated with Eher position. and means 5ncluding said link circuit and one of said trunkN circuits for extending connection from a subscribers line terminating at said first exchange to a subscribers line terminating at said second exchange. and means for rendering all the idle incoming trunk terminals associated with'the operators position at said first exchange busy when het' telephone is connected to one of said subscribers lines.k Y Y 24. A telephone system including telephone lines terminating atla central otlice exchange, other telephone lines terminating at a second central oflice exchange, link circuits vat each of said exchanges, trunk circuits extending from the first of said exchanges to the second of said exchanges for extending calls to said second exch'ange, trunk circuits extending from said ,second exchange'to said first exchange for extending calls from said second exchange to 'said first exchange and terminating in their opposite ends in non-numericalswitchesfor extending said connections, control circuits whereby the connection of a link circuit at said first exchangefto acalling subscrib ers line operates means to 'busy the trunks extending from said second exchange to said first exchange, and circuit connections whereby the connection of said link circuit toa called subscribers line removes the busy indication of said signals.

A telephone system comprising tele-A phone lines terminating at an operators po-y sition. opeiators cord circuits for interconnecting said lines. trunk circuits extending trom said position to other operators positions, non-numerical automatic switchesintermediate said first position and other operators positions for interconnecting the same. an operators telephone for the cord circuits and one for the trunk circuits, means for automatically1 connecting and disconnecting the cord operators telephone and said cord circuits. and akey individual to each cord circuit whereby the cord op,

erators telephone may be connected in circuit with the trunk operators telephone over a conversational circuit independent of that end of the cord circuit distant from thetrunk.

Q6. A telephone system comprising telephone lines terminating at an operators position in an exchange, outgoing trunk circuits extending from said position to other operators positions at avdistant exchange,

'cord circuits for interconnecting said lines at said first exchange or said linesand trimk circuits at said distant exchange.' non-numerical automatic switches between the outgoingends of said first exchange and the incoming terminals of said distant exchange for interconnecting said outgoing and in-y coming terminals of said exchanges. an operators telephone for the cord circuits and one for the trunk circuits. automatic means for connecting the cord operators '.telephone with the cord circuits. telephone lines at said other operators positions. and order wire keys for said -cord circuits for con# necting the operators telephone of a connected cord and a trunk over a conversational circuit including the cord and trunk but independent of that end of. the cord distant from the trunk.

2T. A telephone system comprising tele.- phone lines termina-ting at an operators position, outgoing trunk terminals extending from said position to incoming terminals atanother operators position, telephone linesv terminating at such other position, a'cord circuit for interconnecting the fiist said lilies. non-numerical automatic switches intermediate said outgoing and incoming terminals for interconnecting saidfirst lines and lines at other positions, an opei'ators telephone, automatic means for connecting and disconnecting said operator`s telephone and said cord circuit when it is-used to establish said first connections, and means whereby when a connection is to be extended from a calling line to a distant line through ythe agency of said switches, the cord `operator may order up the connection for the distant line over a. connected cord and trunk to the exclusion of the calling line.

28. A telephone system comprising tele.- phone'lines, an operators linkc-ircuit and a trunk ciiicuit, non-numerical automa-tic Vswitches intermediate said link and trunk circuit, means responsive to the connection of said link circuiti'to a calling line for connecting the operators telephoneA with the link circuit, means responsivel to the connection cuit. to cause said switches to select said link and trunk circuit. means for automatically disconnecting the operators telephone from the link circ-uit, and a key for connect-ing lthe :operators tele'phonevWi-th the link circuit to the exclusion of the calling. line 'so that the operator may order up a connect-ion.

29. A telephone system including telephone lines, an operators position hav`F ing a talking set, a plurality of operators circuits for interchangeable connection to calling lines, said set arranged for inter. changeable. connection to said circuits and so ,tosaidfcalling lines, trunk circuits, automatic selecting mechanism for interconnecting said position'and an idle trunk circuit, an operators talking set at the. distant end of said trunk circuit,- automatic means for. interconnecting said two talking sets over a circ-uitincluding a portion of one 'of said operators circuits `connected with a calling line to the telephonieexclusion of said calling line.

A telephone system including telephone lines and operators positions arranged in groups, link circuits adapted for use Yin linking the lines together for conversation, means whereby an operator extending a connection can' select a group of operators. automatic selecting. and connecting mechanism for said link circuits, talking circuits for said operators, p and control of the link circuit with the trunk cirioov means for directly connecting the talking circuit of said first operator with an idle talking circuit of the group of operators with the aid ot' said mechanism.

3l. A telephone system including lilies. link circuits and operators positions for controlling thc link circuits to interconnect lines` an operators talking circuit at a position. operator's talking sets at other positions, automatic connecting and selecting mechanisms, multiple terminals for each said talking set testing idle or busy according as their set is idle or busy. and control means for causing one of said mechanisms to automatically connect said talking circuit to al set of idle terminals.

32. A telephone system including telephone lines. link circuits and operators positions having means for controlling the circuits to interconnect lines, operators talking ciraiits atsaid positions and automatic selecting and connecting mechanism for connecting one operators talking circuit direct with an idle talking circuit of a group at another operators position` to enable the operators at the connected circuits to converse.

33. A telephone system including telephonel lines, link circuits andoperatois positions having means for controlling the circuits to interconnect lines. means for enabling an operator to extend a call by selecting a group of operatoisl having access to a wanted line. automatic non-restoring selecting mechanism for selecting an idle operator of the group, audible signal means for 'notifying the said firstl operator of the selecting of the idle operator, a talking circuit for the selected operator and automatic means for interconnecting the talking circuits of said first operator and said second operator.

34. A telephone system comprising calling and called'lines. interconnecting link circuits, an operator's position, a distant operators position, automatic selecting and connecting apparatus connected to a link circuiti to extend it toward the called line testmeans controlled/by the listening apparatus at said distant position to prevent such connection from extending to the distant position, and audible signal means at said first. position for notifying the operator thereat that the link circuity is being extended toward the called line.

35. A telephone system including telephone lines, an operators position, an operators telephone set, link circuits for interconnecting said lines. traveling switches for changing the connections of the link circuits, audible signal means and apparatus for controlling it including automaticy means for connecting said operators telephone set in circuit with said audible signal means to notify the operator at. said position that a switch has selected a link circuit, said automatic means operable to disconnect said operators telephone set from said audible signal means after selection has been made.

36. A telephone system including telephone lines. link circuits and operators positions for controlling said circuits to interconnect lines, operators talking circuits at said positions, an operators telephone set. for each of said positions, automatic selecting and connecting mechanism for connecting said talking circuit-s in pairsfto enable the operators at connected circuits to converse, an audible signal and 'automatic means for controlling it and for disconnecting the operators telephone' set at. one position from said audible signal to notify her that her talking circuit-is connected to that of another position.

3T. A telephone system including link circuits, telephone, lines to be interconnected by said link circuits, an operators position, selecting switches operable in a single plane for use in operatively connecting calling lines to said position by the aid of said link circuits and automatic means for preventing said switches from connecting said calling lines to said position ii the operator thereat is busy establishing connections with lines at her position either as calling or called lines.

38. A telephone system including calling and called lines, interconnecting link circuits, selecting switches for interconnecting cert-ain of said circuits in establishing connections, an operators answering plug and apparatus controlled by the insertion of said plug to automatically render some of said circuits u nselectable.

39. A telephone system including a. plurality of lines and link circuits for use in interconnecting then1, automatic selecting switches for extending the link circuits, an operators plug and apparatus etfec-tire on the connection thereof to render a plurality of previously selectable circuits unselectable.

40. A telephone system including a. plurality of lines terminating at operators positions in different exchanges, and link circuits for interconnecting them, selecting switches operable in a single plane for sclecting the link circuits, an operators plug and means controlled, on the connect-ion of said .plug to render a plurality of previously unselectable circuits selectable.

41. A telephone system including operators link circuits and automatic apparatus for connecting the operators telephone to a link circuit, other link circuits and selecting switches controlling apparatus eiective for the connect-ion of said-telephone to said other circuits, and means for preventing such control while said telephone is connected to said first link. circuit.

42. A telephone system including an operators position, a calling line, link circuits and selecting switches for connecting said circuits to said'position, a cord ciroult and answering plug therefor, and apparatus automatically effective on the insertion lof said answering plug to control the operation of said Switches, and automatic' means for said cord circuit controlled over said line for freeing said line from said switch without affecting Said switch.

43. A telephone system comprising callv ing and called lines terminating in dierent exchanges, interconnecting link circuits, an operators position at one of said exchanges, selecting switches operable in a single plane and controlled from said operators posierators telephone, an operators telephoneA tion for uniting certain of said link circuits to other ones of said position, and automatic means eiective on connection by a switch to one of said circuits to render other circuits at said position unselectable. Y

44. Ina telephone system an exchange opat a distant exchange, a non-numerical traveling switch and an automatically controlled audible signal for said iiist operators telephone, its indication changed when said switch ceases to travel, to permit the first exchange operator to converse over a trunk circuit-controlled by said switch withl the operator at said distant exchange.

2k3. In a telephone system a. pair of operators positions located at different exchanges, a non-numerical traveling switch for operatively intercnnecting the positions at said di'ierent exchanges, an automatically controlled audible signal, its changed when said positions are connected, to permit the operators at said connected positions to converse orer a trunk circuit controlled by said' switch.

indication Signed byus at Chicago, county of Cook i and State of Illinois, this 2d day of F ebruary1920.

HIRAM D. CURRIER. vGEORGE R. EATON. 

